1. Field of the Invention
The present invention relates to an electronic device and a remote control system having a remote controller for remotely operating the electronic device.
2. Description of the Related Art
A remote control system which operates a device from a remote place by infrared or wireless communication is widely used in various devices such as TV sets and air conditioners. A general remote control system transmits data corresponding to a pressed button of a remote controller by infrared rays or the like and causes an electronic device which receives the data to execute processing corresponding to the data.
Recently, studies have been made to send voice input to a remote controller as well as data corresponding to a button. Japanese Patent Laid-Open No. 63-245096 discloses a technique of transmitting voice input through a microphone provided for a remote controller upon modulating the voice on a carrier wave such as a radio wave or an ultrasonic wave, and causing an electronic device to receive and process the voice. In addition, “Studies on Practical Use of Voice Recognition Techniques for Home Information Appliances”, 2004 Spring Meeting of the Acoustic Society of Japan 1-8-12 discloses a technique of transmitting voice input through a microphone upon frequency modulation of the voice with infrared rays and causing an electronic device to receive and process the voice.
FIG. 4 is a block diagram of a conventional remote control system configured to transmit voice from a remote controller to an electronic device.
Referring to FIG. 4, reference numeral 401 denotes a remote controller which receives and transmits voice; 402, an electronic device which receives voice and performs predetermined processing for it; 403, a microphone which receives voice in the remote controller 401; 404, a voice transmitter which transmits voice upon modulating it with infrared rays in the remote controller 401; 405, a voice transmission button which issues a voice transmission instruction; 406, an infrared voice carrier which carries voice; 407, a voice receiver which receives the infrared voice carrier 406 in the electronic device 402; and 408, a processor which acquires voice by detecting the reception signal received by the voice receiver 407 and performs predetermined processing for it.
The remote controller 401 receives voice from the microphone 403 only for the period during which the user presses the voice transmission button 405 of the remote controller 401, and causes the voice transmitter 404 to transmit the voice to the infrared voice carrier 406 upon modulating the voice. In the electronic device 402, the voice receiver 407 receives the infrared voice carrier 406 and demodulates it into a voice signal, and the processor 408 acquires the voice signal and executes predetermined processing.
The electronic device 402 in the above remote control system needs to detect the start and end of voice to allow the processor 408 to acquire the voice. It is conceivable to use one of the following three methods as this method.
The first method is to make the voice receiver 407 notify the processor 408 of the start and end of reception of an infrared voice carrier.
The second method is to add start information and data size information to a voice signal and determine the start and end of voice by making the processor 408 read the start information and data size information.
If, however, the voice receiver 407 is an existing module and does not have a function of outputting voice received through an analog signal transmission path such as a LINE output, it is impossible to use the first and second methods. More specifically, in this case, since the voice receiver 407 does not have a function of detecting the start and end of reception of an infrared ray and transmitting it to the processor 408, it is impossible to implement the first method. According to the second method, if voice is digital data, it is easy to add start information and data size information as digital data to voice data and read them. It is, however, difficult to add start information and data size information to an analog voice signal or read the information.
The third method is to make the processor 408 always acquire a voice signal through a LINE input and determine the start and end of the voice based on a feature such as the power value of the voice signal. When, however, a very low voice close to silence is transmitted, this method may erroneously determine that there is no voice or, when no voice is transmitted, may erroneously determine that voice is input, due to device noise on the transmission path. In order to unfailingly transmit voice input from the microphone 403, including silence, to the processor, it is impossible to use this method.
It is therefore necessary to use another method which allows the processor 408, which acquires an analog voice signal from the LINE input, to determine the start and end of voice.